Sound attenuating device using an embedded layer for acoustical tuning

ABSTRACT

The present invention includes a layered acoustical system for sound attenuation in a vehicle including an external decorative layer; a moldable fiber backer adhesively adhered to a back side of the decorative layer, the moldable fiber backer further including an engineered fiber blend including one or more types of thermoplastic fibers and having a first density; a moldable lofted sound absorber and vibration decoupling layer including being made from another engineered fiber blend including one or more types of thermoplastic fibers and having a second density that is less than the first density of the moldable backer, a top side of the vibration decoupling layer being adhesively adhered to the second side of the moldable fiber backer; and an intermediate layer embedded in a location within the vibration decoupling layer to achieve a balance point between transmission loss and sound absorption.

FIELD OF THE INVENTION

This invention relates to molded structural acoustical parts. Morespecifically, the invention relates to a sound attenuating device havingan embedded layer for acoustical tuning for use in a vehicle.

SUMMARY

The invention describes a tunable, layered acoustical system for soundattenuation in a vehicle including an external decorative layer that canbe tufted or needled; a moldable fiber backer including a first side anda second side, the first side of the moldable fiber backer beingadhesively adhered to a back side of the external decorative layer, themoldable fiber backer further including an engineered fiber blendincluding one or more types of thermoplastic fibers, the moldable fiberbacker having a first surface density; a moldable lofted sound absorberand vibration decoupling layer including a top side and a bottom sideand being made from the same or another engineered fiber blend includingone or more types of thermoplastic fibers, the moldable lofted soundabsorber and vibration decoupling layer having a second surface densitythat is less than the first surface density of the moldable backer, thetop side of the moldable lofted sound absorber and vibration decouplinglayer being adhesively adhered to the second side of the moldable fiberbacker; and an intermediate layer embedded in and adhered to a locationwithin the moldable lofted sound absorber and vibration decoupling layerto achieve a balance point between transmission loss and soundabsorption.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention. Theinvention will be best understood by reading the ensuing specificationin conjunction with the drawings, in which same numbered elements areidentical.

Embodiments will hereinafter be described in detail below with referenceto the accompanying drawings, wherein like reference numerals representlike elements. The accompanying drawings have not necessarily been drawnto scale. For example, tilt angles and feature sizes may be exaggeratedin the figures. Where applicable, some features may not be illustratedto assist in the description of underlying features.

FIG. 1 is a cross-sectional, side view of a sound attenuating devicehaving an acoustical perforated film layer embedded in a decouplinglayer, in accordance with one or more embodiments of the presentinvention.

FIG. 2 is a graph showing the transmission loss and sound absorption ofthe sound attenuating device of FIG. 1.

FIG. 3 a cross-sectional, side view of a sound attenuating device havingan acoustical perforated film layer embedded in a cap or moldable backerlayer, in accordance with one or more embodiments of the presentinvention.

FIG. 4 is a cross-sectional, side view of a sound attenuating devicehaving an acoustical perforated film layer embedded in a decouplinglayer as in FIG. 1 a but without a top decorative layer, in accordancewith one or more embodiments of the present invention.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the disclosedsubject matter. However, it will be understood by those of ordinaryskill in the art that the present invention may be practiced withoutthese specific details. In other instances, well-known methods,procedures and components may not have been described in detail so asnot to obscure aspects of the disclosed subject matter.

Embodiments of the present invention are directed generally to a soundattenuating device having an embedded layer. In particular, embodimentsof the present invention relate to a sound attenuating device having anembedded acoustical layer. As used herein, the phrase “variousembodiments” is intended to mean an embodiment, at least one embodiment,some embodiments, and/or all embodiments without limitation.

The present invention includes (i.e., comprises) a tunable, multi-layer,sound attenuating device having a separate thickness and density foreach layer so that the device functions to achieve a balance pointbetween transmission loss and sound absorption for use in thetransportation industry, for example, but not limited to, as a passengercompartment carpet in automobiles or a dash insulator, generally,without a decorative layer. In accordance with at least one embodimentof the present invention, a first, or top, layer of the device is adecorative layer that can be tufted or needled, for example, anon-tufted and un-backed carpet having a thickness of about 5 mm, aweight of about 19 oz and an airflow resistance of about 80 Rayls (N·m⁻³s). A second, or backer or cap, layer of the device is a moldable backerlayer having, for example, a surface density of approximately 807 gsm, athickness of approximately 3 mm and an air flow resistance (AFR) ofapproximately 400 Rayls. The moldable backer layer is located below thefirst layer and a top surface/side of the moldable backer layer isadhesively adhered to a bottom layer/side of the first layer. A third,or decoupling, layer of the device is a moldable lofted sound absorberand vibration decoupling layer having, for example, a surface density ofapproximately 1610 gsm, a thickness of approximately 3 to 30 mm and anAFR of approximately 490 Rayls. In various embodiments of the presentinvention, the moldable lofted sound absorber and vibration decouplinglayer may have embedded within it an intermediate acoustical layer. Theembedded intermediate acoustical layer can include, but is not limitedto, a perforated film layer, an unperforated film layer, a scrim layer,or a paper layer. The perforated film layer may have, for example, athickness of approximately 0.5 mm, multiple approximately 380 micron (μ)diameter and substantially circular perforations in the two-dimensional(i.e., the unmolded) configuration with a hole density of approximately30 holes/in², an AFR of 900 Rayls, and be constructed of one or morelayers of polyamide, polyethylene, polyethylene terephthalate (PET)and/or polypropylene. The shape of the perforations may be differentafter the device is molded to fit the desired vehicle configuration. Forexample, they may be elongated, curved, oval, reduced in diameter, etc.,depending on the extent of the molding performed at each perforationlocation. The perforations may also be sized between 200μ and 500μ. Thescrim layer may include a third fiber blend having, for example, asurface density of 90 gsm, a thickness of approximately 0.3 mm and anAFR of approximately 2000 Rayls.

Dissipative fiber systems, in accordance with one or more embodiments ofthe present invention, have improved either absorption or insertion lossin the critical 800 Hz range—as identified in vehicle road tests.Several of the systems showed tradeoffs between absorption andtransmission loss (TL) and, in general, it was discovered that higherabsorption comes with lower TL, but the frequency spectrum at issue mustbe examined in order to select a system that works best in the vehicle.Tuning of the system can be accomplished by changes in the fiber cap,the acoustical control layer and the fiber decoupler.

A layered construction for sound attenuation in a vehicle includes anexternal decorative layer (e.g., a carpet layer); a moldable backer forthe decorative layer made from an engineered fiber blend including oneor more types of thermoplastic fibers; a moldable lofted layer acting asa combined sound absorber and vibration decoupler made from anengineered fiber blend including one or more types of thermoplasticfibers; an intermediate layer that can be embedded at multiple locationsin the construction for acoustical tuning The intermediate layer can bea perforated membrane or film, an impermeable membrane or film, or anacoustical control layer with preferred air flow control properties.

The type of film, the perforations, and the location of the film withinany layer are selected to provide a balance between the sound absorptioncoefficient and the transmission loss for the construction. Both ofthese properties are critical to sound attention in a vehicle. Theconstruction can also be used without a decorative layer when thesurface is not visible (e.g., under dash insulator). The constructionprovides sound attenuation equivalent to higher mass barrier systemswhile providing weight saving for fuel economy and more efficientinstallation.

Additional design features can include: a control layer embedded withinone or more of the fiber layers and not only used to separate dissimilarlayers, for example, but not limited to, one or more layers within thedecoupling layer, one or more layers in the backer layer, and/or one ormore layers in at least two of the decoupling layer, and the backerlayer; a perforated film as the control layer where performance isdefined by film thickness, perforation size, and % open area; an AFRlayer as the control layer—also embedded within one or more of the fiberlayers; a perforated film or AFR layer as the embedded control layerwhere performance is controlled by preferential placement at differentdepths within the fiber layers; a film made of 3 or more layers that canbe easily perforated prior to assembly with a hole size critical to therequired performance and that is integral to the assembly; multiplefiber layers used for the moldable backer and that are in contact withboth sides of the control layer; a special fiber blend for the moldablebacker chosen for improved sound absorption over a standard fiber blend;a special fiber blend for the lofted vibration decoupler (i.e., thedecoupling layer) chosen for improved sound absorption and transmissionloss over a standard fiber blend; and a product design that provides arequired TL without further compromising TL.

FIG. 1 is a cross-sectional, side view of a sound attenuating devicehaving an acoustical perforated film layer embedded in a decouplinglayer, in accordance with one or more embodiments of the presentinvention. In FIG. 1, a sound attenuating device 100 is shown to includea moldable decoupling layer (i.e., a decoupler) 110, for example, actingas a lofted sound absorber and vibration decoupling layer 110, which canbe between 5 and 30 mm thick and be made of a moldable fiber blend.Embedded within the moldable decoupling layer 110 is seen an acousticalcontrol layer 120, which is a perforated film layer 120. In general, theacoustical control layer 120 is positioned in the moldable decouplinglayer 110 between ½ and ⅔ the way above a bottom side of the moldabledecoupling layer 110. A top side of the moldable decoupling layer 110 isattached to a bottom side of a moldable backer 130 or cap layer 130,which in turn has top side attached to a bottom side of a decorativelayer 140. Attachment of the layers may be accomplished using adhesive,needling, heat bonding, etc., as well as any combination thereof.

FIG. 2 is a graph showing the insertion loss and sound absorption of thesound attenuating device of FIG. 1. As seen in FIG. 2, a point ofmaximum transmission loss and maximum sound absorption 200 for thedevice in FIG. 1 is shown in the top right of the graph in FIG. 2. Thetransmission loss and sound absorption at each frequency is alsocritical to the overall performance.

FIG. 3 a cross-sectional, side view of a sound attenuating device havingan acoustical perforated film layer embedded in a cap or moldable backerlayer, in accordance with one or more embodiments of the presentinvention. In FIG. 3, a sound attenuating device 300 is shown to includea moldable decoupling layer (decoupler) 310, for example, a moldablelofted sound absorber and decoupling layer 310, which can be between 5and 30 mm thick and be made of a moldable fiber blend, a moldable backeror cap layer 330, an acoustical control layer 320 and a decorative layer340. Embedded within the moldable backer layer 330 is the acousticalcontrol layer 320, which is a perforated film layer 320. In general, theacoustical control layer 320 will be positioned in the moldable backerlayer 330 between ½ and ⅔ above a bottom side of the moldable backerlayer 330. A top side of the moldable decoupling layer 310 is attachedto a bottom side of a moldable backer or cap layer 330, which in turnhas a top side attached to a bottom side of the decorative layer 340.Attachment of the layers may be accomplished using adhesive, needling,heat bonding, etc., as well as any combination thereof.

FIG. 4 is a cross-sectional, side view of a sound attenuating device 400having an acoustical perforated film layer 420 embedded in a decouplinglayer 410 as in FIG. 1 but without a top decorative layer, in accordancewith one or more embodiments of the present invention. A top side of thedecoupling layer 410 is attached to a bottom side of a moldable caplayer 430. Although not shown in any figures, the other embodimentsshown and/or described herein may also have alternate versions withoutthe decorative layer.

Other embodiments are also contemplated to include in one embodiment anAFR scrim layer embedded in the cap portion (i.e., the moldable backerlayer), a needled film in the cap portion, an AFR scrim layer betweenthe decorative and moldable backer layers.

In accordance with one or more embodiments of the present invention alayered acoustical system for sound attenuation in a vehicle includes anexternal decorative layer; a moldable fiber backer including a firstside and a second side, the first side of the moldable fiber backerbeing adhesively adhered to a back side of the decorative layer, themoldable fiber backer further including an engineered fiber blendincluding one or more types of thermoplastic fibers, the moldable fiberbacker having a first density; a moldable lofted sound absorber andvibration decoupling layer including a top side and a bottom side andbeing made from the same or another engineered fiber blend including oneor more types of thermoplastic fibers, the moldable lofted soundabsorber and vibration decoupling layer having a second density that isless than the first density of the moldable backer, the top side of themoldable lofted sound absorber and vibration decoupling layer beingadhesively adhered to the second side of the moldable fiber backer; andan intermediate layer embedded in a location within the moldable loftedsound absorber and vibration decoupling layer to achieve a balance pointbetween transmission loss and sound absorption.

In accordance with one or more embodiments of the present invention alayered acoustical system for sound attenuation in a vehicle includes amoldable fiber cap layer including a first side and a second side, thefirst side of the moldable fiber cap layer being uncovered; the moldablefiber cap layer further including an engineered fiber blend includingone or more types of thermoplastic fibers, the moldable fiber cap layerhaving a first density; a moldable lofted sound absorber and vibrationdecoupling layer including a top side and a bottom side and being madefrom the same or another engineered fiber blend including one or moretypes of thermoplastic fibers, the moldable lofted sound absorber andvibration decoupling layer having a second density that is less than thefirst density of the moldable fiber cap layer, the top side of themoldable lofted sound absorber and vibration decoupling layer beingadhesively adhered to the second side of the moldable fiber cap layer;and an intermediate layer embedded in and adhered to a location withinthe moldable lofted sound absorber and vibration decoupling layer toachieve a balance point between transmission loss and sound absorption.

In accordance with one or more embodiments of the present invention, alayered acoustical system for sound attenuation in a vehicle includes:an external, decorative layer; a moldable fiber backer including a firstside and a second side, the first side of the moldable fiber backerbeing adhesively adhered to a back side of the external, decorativelayer, the moldable fiber backer further including an engineered fiberblend including one or more types of thermoplastic fibers, the moldablefiber backer having a thickness of about 3 mm and a surface density ofabout 807 gsm; a moldable lofted sound absorber and vibration decouplinglayer including a top side and a bottom side and being made from anotherengineered fiber blend including one or more types of thermoplasticfibers, the moldable lofted sound absorber and vibration decouplinglayer having a thickness in the range of from 3 to 30 mm and a surfacedensity of about 1610 gsm, the top side of the moldable lofted soundabsorber and vibration decoupling layer being adhesively adhered to thesecond side of the moldable fiber backer; the external, decorativelayer, the moldable fiber backer and the moldable lofted sound absorberand vibration decoupling layer having a balance between sound absorptionand transmission loss; and a perforated film layer including a heatactivated adhesive on opposite sides of the perforated film layer, theperforated layer having a thickness of about 0.5 mm, a plurality ofperforations each having a diameter of about 380μ, a hole density ofabout 30 holes/in², and an airflow resistance of approximately 900Rayls, the perforated layer being embedded in and adhered to a locationwithin the decoupling layer, the layered acoustical system beingconstructed to achieve a balance between sound absorption andtransmission loss. The layered acoustical system for sound attenuationwherein the perforated film layer in the decoupling layer is located ata level about ½ to ⅓ the thickness of the decoupling layer away from thefirst side of the decoupling layer.

While the present invention has been described in conjunction with anumber of embodiments, the invention is not to be limited to thedescription of the embodiments contained herein. It is further evidentthat many alternatives, modifications, and variations would be or areapparent to those of ordinary skill in the applicable arts. Accordingly,all such alternatives, modifications, equivalents, and variations thatare within the spirit and scope of this invention are included.

What is claimed is:
 1. A layered acoustical system for sound attenuationin a vehicle comprising: an external decorative layer; a moldable fiberbacker having a first density and a first side of the moldable fiberbacker being adhered to a back side of the external decorative layer,the moldable fiber backer further including a first engineered fiberblend including thermoplastic fibers; a moldable lofted sound absorberand vibration decoupling layer being made from a second engineered fiberblend including thermoplastic fibers, the moldable lofted sound absorberand vibration decoupling layer having a second density that is less thanthe first density of the moldable backer, a top side of the moldablelofted sound absorber and vibration decoupling layer being adhered to asecond side of the moldable fiber backer; and an intermediate layerembedded in and adhered to a location within the moldable lofted soundabsorber and vibration decoupling layer to achieve a balance pointbetween transmission loss and sound absorption.
 2. The layeredacoustical system of claim 1 wherein the decorative layer is a tuftedcarpet, a needled non-woven carpet, or a nonwoven carpet with athickness of approximately 5 mm, and an airflow resistance ofapproximately 80 Rayls.
 3. The layered acoustical system of claim 1wherein the intermediate layer is an acoustical control layer includinga perforated membrane or film that comprises at least one layer, animpermeable membrane, or an airflow resistance layer with preferred airflow control properties comprising a third fiber blend having a densityof approximately 90 gsm, a thickness of approximately 0.3 mm, and anairflow resistance of approximately 2000 Rayls.
 4. The layeredacoustical system of claim 1 wherein the intermediate layer is aperforated film layer made of polyamide and polyethylene and having anunmolded thickness of approximately 0.5 mm, a plurality of approximately380 μ diameter substantially circular perforations, a hole density ofapproximately 30 holes/in², and an airflow resistance of approximately900 Rayls.
 5. The layered acoustical system of claim 1 wherein themoldable fiber backer has a surface density of approximately 807 gsm, athickness of approximately 3 mm, and an airflow resistance ofapproximately 400 Rayls.
 6. The layered acoustical system of claim 1wherein the moldable lofted sound absorber and vibration decouplinglayer has a surface density of approximately 1610 gsm, a thickness inthe range of approximately 3 mm to approximately 30 mm, and an airflowresistance of approximately 490 Rayls at 30 mm.
 7. The layeredacoustical system of claim 1 wherein the location of the perforated filmlayer in the moldable lofted sound absorber and vibration decouplinglayer is at a level about ½ to ⅓ the thickness of the moldable loftedsound absorber and vibration decoupling layer away from the top side ofthe moldable lofted sound absorber and vibration decoupling layer. 8.The layered acoustical system of claim 1 further comprising a secondperforated film layer embedded in and adhered to a location within themoldable backer, the layered acoustical system still constructed toachieve a new balance point between transmission loss and soundabsorption.
 9. The layered acoustical system of claim 3 wherein thelocation of the air flow resistance layer in the moldable lofted soundabsorber and vibration decoupling layer is at a level about ⅓ thethickness of the moldable lofted sound absorber and vibration decouplinglayer away from the top side of the moldable lofted sound absorber andvibration decoupling layer.
 10. The layered acoustical system of claim 1further comprising an air flow resistance layer embedded in and adheredto a location within the moldable backer, the layered acoustical systemstill constructed to achieve a new balance point between transmissionloss and sound absorption.
 11. The layered acoustical system of claim 1further comprising a second air flow resistance layer embedded in andadhered to a location within the moldable backer, the layered acousticalsystem constructed to achieve a new balance point between transmissionloss and sound absorption.
 12. The layered acoustical system of claim 1further comprising an impermeable membrane layer embedded in and adheredto a location within the moldable backer, the layered acoustical systemstill constructed to achieve a new balance point between transmissionloss and sound absorption.
 13. A layered acoustical system for soundattenuation in a vehicle comprising: a moldable fiber cap layerincluding a first side of the moldable fiber cap layer being uncovered,the moldable fiber cap layer further including an engineered fiber blendof thermoplastic fibers, the moldable fiber cap layer having a firstdensity; a moldable lofted sound absorber and vibration decoupling layermade from another engineered fiber blend of thermoplastic fibers, themoldable lofted sound absorber and vibration decoupling layer having asecond density that is less than the first density of the moldable fibercap layer, a top side of the moldable lofted sound absorber andvibration decoupling layer being adhered to a second side of themoldable fiber cap layer; and an intermediate layer embedded in andadhered to a location within a single layer of the layered acousticalsystem to achieve a balance point between transmission loss and soundabsorption.
 14. The layered acoustical system of claim 13 wherein thelocation of the intermediate layer is in the moldable lofted soundabsorber and vibration decoupling layer.
 15. The layered acousticalsystem of claim 14 wherein the location of the intermediate layer in themoldable lofted sound absorber and vibration decoupling layer is at alevel about ½ to ⅓ the thickness of the moldable lofted sound absorberand vibration decoupling layer away from the top side of the moldablelofted sound absorber and vibration decoupling layer.
 16. The layeredacoustical system of claim 13 wherein the location of the intermediatelayer is in the moldable fiber cap layer.
 17. The layered acousticalsystem of claim 13 wherein the embedded intermediate layer is aperforated membrane or film, an impermeable membrane, or an acousticalcontrol layer with preferred air flow control properties.
 18. A layeredacoustical system for sound attenuation in a vehicle comprising: anexternal decorative layer; a moldable fiber backer including a firstside of the moldable fiber backer being adhered to a back side of theexternal, non-tufted and un-backed decorative layer, the moldable fiberbacker further including an engineered fiber blend of thermoplasticfibers, the moldable fiber backer having a thickness of about 3 mm and adensity of about 807 gsm; a moldable lofted sound absorber and vibrationdecoupling layer being made from another engineered fiber blend ofthermoplastic fibers, the moldable lofted sound absorber and vibrationdecoupling layer having a thickness in the range of from 3 to 30 mm anda density of about 1610 gsm, a top side of the moldable lofted soundabsorber and vibration decoupling layer being adhered to a second sideof the moldable fiber backer; and a perforated film layer including aheat activated adhesive on opposite sides of the perforated film layer,the perforated layer having a thickness of about 0.5 mm, a plurality ofperforations each having a diameter of about 380 μ and a hole density ofabout 30 holes/in², and an airflow resistance of approximately 900Rayls, the perforated layer being embedded in and adhered to a locationwithin the moldable lofted sound absorber and vibration decoupling layerto achieve a balance point between transmission loss and soundabsorption.
 19. The layered acoustical system of claim 18 wherein thelocation of the perforated film layer in the moldable lofted soundabsorber and vibration decoupling layer is at a level about ½ to ⅓ thethickness of the moldable lofted sound absorber and vibration decouplinglayer away from the top side of the moldable lofted sound absorber andvibration decoupling layer.
 20. The layered acoustical system of claim18 wherein the decorative layer is a tufted carpet, a needled non-wovencarpet, or a nonwoven carpet with a thickness of approximately 5 mm, andan airflow resistance of approximately 80 Rayls.